Metering and leveling screed device

ABSTRACT

The present invention is directed to a screed assembly that includes a strike-off. This strike-off is directly connected to a screed plate such that the strike-off is able to bend or twist along with movement of the screed plate which occurs during a paving operation. The strike-off in the screed assembly of the present invention is simpler and less costly to manufacture than corresponding devices in existing screed assemblies. Connecting the strike-off directly to the screed establishes a shearing height prior to mounting the screed assembly to the paving machine in set up of the screed assembly faster and easier to accomplish.

[0001] This application claims priority to provisional application Ser.No. 60/186,779, filed Mar. 3, 2000, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to paving vehicles, and moreparticularly to screed assemblies used with paving vehicles.

BACKGROUND OF THE INVENTION

[0003] Paving vehicles or pavers having floating screed assemblies areknown, an example of one such screed assembly 1 being shown in FIG. 1.Generally, a conventional screed assembly 1 is pivotally attached to apaver vehicle chassis (not shown) and has a screed plate 2 mountedbeneath a frame 3. The screed plate 2 has a lower surface 2 a whichlevels paving material into a material mat (not depicted) having adesired height or thickness as the paver vehicle moves forwardly in apaving direction.

[0004] Typically, these screed assemblies 1 also include a strike-offdevice 4 adjustably attached to the screed frame 3 which shears offpaving material to an initial height prior to being leveled by thescreed plate 2. Strike-off devices 4 typically include avertically-extending plate 5 providing a strike-off edge 4 a at thelower end thereof and an adjustment mechanism 6 for adjusting the heighth_(o) of the edge 4 a with respect to the working surface 2 a. Forexample, the adjustment mechanism 6 may include one or more rods 7having an end 7 a attached to the strike-off plate 5 and a portion 7 bmovably mounted to the frame 3, such that movement of the rod 7 withrespect to the frame 3 adjusts the height h_(o).

[0005] With such screed assemblies 1, as discussed above, it isnecessary to adjust the strike-off edge 4 a to the desired height h_(o)with respect to the screed working surface 2 a prior to commencing apaving operation. Thus, such adjustment of the strike-off device 4increases the set-up time of the screed assembly 1. As screed plates 2become worn and must be periodically replaced, the strike-off device 4is typically adjusted numerous times over the life of the screedassembly 1. Further, as paving material generally causes a certainamount of bending and/or twisting of the screed plate 2 during a pavingoperation, the height h_(o) between the strike-off edge 4 a and theworking surface 2 a will become varied across the width of the screedassembly 1. These unintended variations of the strike-off height h_(o)effect the amounts of paving material metered to the screed plate 2,such that sections/portions of a finished material mat may be formed atother than a desired thickness.

SUMMARY OF THE INVENTION

[0006] Therefore, it is desirable to provide a screed assembly 1 that isquicker and easier to set-up before use. Further, it is also desirableto provide a strike-off device that is simpler and requires lessmaterial to manufacture than known strike-off devices. Furthermore, itis desirable to prevent variations in the height or spacing of astrike-off edge with respect to a screed working surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The foregoing summary, as well as the detailed description of thepreferred embodiments of the invention, will be better understood whenread in conjunction with the appended drawings. For the purpose ofillustrating the invention, there is shown in the drawings, which arediagrammatic, embodiments that are presently preferred. It should beunderstood, however, that the invention is not limited to the precisearrangements and instrumentalities shown. In the drawings:

[0008]FIG. 1 is a side elevational view of a screed assembly with aknown type of strike-off device;

[0009]FIG. 2 is a side elevational view of a screed assembly having ametering and leveling screed device in accordance with the presentinvention;

[0010]FIG. 3 is a top perspective view of the present screed device; and

[0011]FIG. 4 is an exploded side view of the present screed device.

DETAILED DESCRIPTION OF THE INVENTION

[0012] Certain terminology is used in the following description forconvenience only and is not limiting. The words “lower”, “upper”, and“upward” designate directions in the drawings to which reference ismade. The words “front” and “rear” refer to directions toward and awayfrom, respectively, a designated front section of a screed assembly, ametering and leveling screed device or a specific portion of either, theparticular meaning intended being readily apparent from the context ofthe description. The terminology includes the words specificallymentioned above, derivatives thereof, and words of similar import.

[0013] Referring now to the drawings in detail, wherein like numbers areused to indicate like elements throughout, there is shown in FIGS. 2-4 ametering and leveling screed device 10 comprising a leveling portion,preferably a screed plate 12, and a metering portion, preferably astrike-off 14 connected to the screed plate 12. Preferably, thestrike-off 14 is fixedly attached to the screed plate 12, as depicted inFIGS. 2 and 3, although the strike-off 14 may alternatively beadjustably attached to, or even integrally formed with, the screed plate12, as discussed in further detail below. The strike-off 14 portion ofthe device 10 shears upper portions of a deposit or “head” of pavingmaterial in order to meter appropriate amounts of paving material to thescreed plate 12 portion of the device 10 for subsequent leveling andcompacting, as discussed in further detail below.

[0014] The screed plate 12 is preferably formed similar to aconventional screed plate 2. Specifically, the plate 12 is primarily ofone piece-construction and includes a generally horizontal base section16 and a generally vertical rail section 18 extending upwardly along thefront end of the base section 16. The lower surface of the base section16 provides the working or leveling surface 15 of the screed assemblyand functions to level paving material deposited on a base surface, asis well known. Further, a plurality of mounting studs 25 extend from theupper surface of the base section 16 and are configured for mounting thescreed plate 12, and thus the device 10, to the screed assembly 1 in aconventional manner.

[0015] The rail section 18 has a front surface 20 that includes a lower,curved lead-in or channeling surface section 20 a that functions tochannel paving material to the working surface 15. Further, the railsection front surface 20 also includes an upper, generally flatattachment surface section 20 b configured to connect with thestrike-off 14. The rail section 18 further includes a plurality ofmounting holes 21 (FIG. 4—one shown) spaced horizontally across theattachment surface section 20 b, the purpose of which is describedbelow. Besides providing the respective lead-in and attachment surfacesections 20 a and 20 b and the mounting holes 21, the rail section 18also operates as a barrier to prevent paving material from flowing onto,and accumulating upon, the upper surface of the screed plate 12.

[0016] Preferably, the screed plate 12 is fabricated by bending one edgeof generally flat plate in a (lie-forming operation so as to form therail section 18 and then welding the studs 25 onto the upper surface ofthe base section 16. Further, the screed plate 12 is preferablyconstructed of high carbon steel, most preferably either WELDOX™ orHARDOX™ commercially available grades of steels. Alternatively, thescreed plate 12 may be formed using any other appropriate manufacturingtechnique, such as for example casting, and/or may be constructed onanother appropriate material, for example low carbon steel that has beenappropriately hardened such as by carburization.

[0017] Referring again to FIGS. 2-4, preferably, the strike-off 14includes one or more (two shown) generally flat and narrow,rectangular-shaped plates or “blades” 22 having a generally uniformthickness. The lower end of each strike-off blade 22 provides theworking or “strike-off” edge 24, as discussed below. Each blade 22 has agenerally flat rear surface 22 a that is configured to be disposedagainst the attachment surface section 20 b of the screed plate 12, asdiscussed below. Further, a plurality of horizontally-spaced mountingholes 26 (FIG. 4—one shown) extend through each blade 22, which areconfigured to align with the mounting holes 21 in the rail section 18 ofthe screed plate 12, as discussed below. Preferably, the strike-offblades 22 are stamped from low carbon steel, although the strike-off 14may alternatively be fabricated using any other appropriate materialand/or manufacturing technique, such as for example, being machined fromtool steel (although not preferred due to costs).

[0018] Although the strike-off 14 is preferably constructed as twogenerally flat blades 22 as described above, the strike-off 14 mayalternatively be formed in any other appropriate configuration that iscapable of being attached to the screed plate 12. For example, thestrike-off 14 may include only a single blade or three or moreblades/blade sections (neither shown). Further, the blades 22 may eachhave varying thickness, such as being tapered or stepped, between theupper and lower ends of the blade 22, as opposed to being of uniformthickness. Further for example, the strike-off 14 may be constructed asbended or angled plate (not shown) having a lower end extendingforwardly from an upper end, so that the strike-off edge 24 is spacedsubstantially forwardly of the screed plate 12, particularly if it isdesired that the strike-off 14 perform a material “plowing” function aswell as shearing.

[0019] As yet another example, the edges 24 of the two blades 22 mayeach be angled so as to extend upwardly from a blade outer end (i.e.,outer with respect to center of device 10) to a blade inner end (notshown), or a single blade may have an equivalent triangular-shaped edge(not shown), such that a greater amount of material is metered under thecentral region of the screed plate 12. As an even further example, thestrike-off 14 may be constructed of two or more pieces, such as one ormore brackets attachable to the screed plate 12 and a blade(s) mountableto the brackets (not shown). The present invention includes the abovealternative constructions of the strike-off 14 and any other appropriateconfiguration that enables the strike-off 14 to be directly attached tothe screed plate 12.

[0020] Referring again to FIGS. 2 and 3, the strike-off 14 is mounted tothe screed plate 12 by placing the rear blade surfaces 22 a against theattachment surface section 20 b of the rail 18 such that the severalpairs of mounting holes 21 and 26 are aligned, and then insertingthreaded fasteners 27 through the mounting hole pairs 21 and 26. In thepreferred construction as described, the strike-off 14 is fixedly ornon-adjustably attached to the screed plate 12. Therefore, when thestrike-off 14 is attached as described, the strike-off edge 24 isautomatically established at a desired height h_(d) (FIG. 2) withrespect to the leveling surface 15.

[0021] Alternatively, the strike-off 14 may be non-removably attached tothe screed plate 12, such as by forming a riveted or welded jointbetween the strike-off blade 22 and the rail section 18. As anotheralternative, the strike-off 14 may be integrally formed with the screedplate 12, such as by die-forming or casting the entire screed device 10so as to be of one-piece construction.

[0022] As an even further alternative, the strike-off 14 may beadjustably (and removably) attached to the screed plate 12, such as byproviding slotted openings in place of one (or both) sets of mountingholes 21 and 26. With an adjustably attached strike-off plate 14(configuration not depicted), the strike-off edge 24 should be adjustedto the desired height h_(d) prior to attaching the device 10 to theframe 3, although such adjustment may alternatively be performed aftermounting of the device 10.

[0023] Prior to use, as mentioned above, the metering and levelingscreed device 10 is attached to the frame 3 of a screed assembly 1 in agenerally identical manner as a conventional screed plate 2.Specifically, the mounting studs 25 are each inserted through a matingopening (not shown) in the screed frame 3 and are engaged by nuts (notshow) to removably mount the screed device 10 to the frame 3. As thestrike-off edge 24 is preferably at a specific, desired height h_(d)with respect to the leveling surface 15, no further adjustment of thescreed device 10 should be necessary.

[0024] Although the metering and leveling screed device 10 of thepresent invention is depicted in FIG. 2 as being mounted to a single“main” screed assembly 1, it is within the scope of the p-resentinvention to use the present screed device 10 with any type of screedassembly 1 that is configured to include one or more screed plates. Forexample, the screed device 10 may be mounted to a single main screedconfigured for a single screed plate, to a main screed formed of twoscreed halves (thus having two screed plates) so as to provide crowning,to a fixed screed extension, and/or to a laterally movable or“extendable” screed extension. Thus for example, a screed assembly 1including a main screed formed of two “crownable” screed halves and twoextendable screed extensions (not shown) may include four screed devices10 of the present invention. Thus, the present invention is not limitedto being used with any specific type of screed assembly 1.

[0025] In use, as the screed assembly 1 is pulled forwardly by the pavervehicle (not shown), the strike-off edge 24 “shears off” upper portionsof a mass of paving material deposited forwardly of the assembly 1 bythe paver vehicle, and thereby establishes a first material height ormaterial level of the material. Then, paving material is channeled byaction of the channeling surface section 20 a of the screed plate 12 soas to flow beneath the leveling surface 15. The screed leveling surface15 then levels and preferably also compacts the paving material into amaterial mat (not shown) having a desired thickness or height (notshown).

[0026] Providing a screed assembly 1 with the metering and levelingscreed device 10 of the present invention is clearly advantageous overprior screed assemblies 1 having a separate screed plate 2 and aseparate strike-off device 4. First, by having the strike-off 14directly connected to the screed plate 12, the strike-off 14 is able tobend or twist along with such movement of the screed plate 12 occurringduring a paving operation, such that the desired strike-off height h_(d)is generally always maintained. Further, the strike-off 14 portion ofthe present device 10 is much simpler and less costly to produce than astrike-off device 4 having a large plate 5 and an adjustment mechanism 6including one or more movable rods 7. Furthermore, by being able toestablish the desired height h_(d) prior to mounting the device 10 tothe screed assembly 1, either automatically when attaching the blade(s)22 to the rail 18 or by adjusting the blade(s) before mounting thedevice 10, the set-up of a screed assembly 1 with the device 10 isfaster and easier to accomplish than separately adjusting the verticalstrike-off plate 5 with respect to a separate screed plate 2.

[0027] It will be appreciated by those skilled in the art that changescould be made to the embodiments described above without departing fromthe broad inventive concept thereof. It is understood, therefore, thatthis invention is not limited to the particular embodiments disclosed,but it is intended to cover modifications within the spirit and scope ofthe present invention as generally and illustratively described herein.

1. A screed assembly for use with a paving machine, the screed assemblycomprising: a screed including a front portion, a rear portion and arounded portion positioned between the front portion and the rearportion; and a strike-off coupled to the screed.
 2. The screed assemblyof claim 1 wherein the strike-off is coupled to the front portion of thescreed.
 3. The screed assembly of claim 2 wherein the front portion ofthe screed includes a front surface such that the strike-off is coupledto the front surface on the front portion of the screed.
 4. The screedassembly of claim 3 wherein the strike-off includes a rear surface suchthat the rear surface of the strike-off is coupled to the front surfaceon the front portion of the screed.
 5. The screed assembly of claim 4wherein the rear surface of the strike-off and the front surface of thefront portion are substantially flat.
 6. The screed assembly of claim 1wherein the strike-off is integral with the screed.
 7. The screedassembly of claim 1 wherein the screed plate has a one-piececonstruction.
 8. The screed assembly of claim 1 wherein the rear portionof the screed includes a lower leveling surface for compacting pavingmaterial.
 9. The screed assembly of claim 8 wherein the rear portion ofthe screed includes at least one stud extending outwardly from an uppersurface on the rear portion, the screed assembly being secured to aframe on the paving machine by securing the stud to the frame of thepaving machine.
 10. The screed assembly of claim 1 wherein thestrike-off and the screed each include aligned mounting holes, and thestrike-off is connected to the screed using fasteners that extendthrough the aligned mounting holes.
 11. The screed assembly of claim 1wherein the strike-off is welded to the screed.
 12. The screed assemblyof claim 1 wherein the strike-off is made from low carbon steel.
 13. Thescreed assembly of claim 1 wherein the screed is made from high carbonsteel.
 14. The screed assembly of claim 1 wherein the strike-offincludes at least one blade.
 15. The screed assembly of claim 14 whereinthe strike-off includes two blades.
 16. The screed assembly of claim 15wherein each of the blades is rectangular.
 17. The screed assembly ofclaim 15 wherein each of the blades has a substantially uniformthickness.
 18. The screed assembly of claim 15 wherein each of theblades is formed from angled plate material.
 19. The screed assembly ofclaim 1 wherein the strike-off is riveted to the screed.
 20. The screedassembly of claim 1 wherein the strike-off includes slotted openings andthe screed includes mounting holes which are aligned with the slottedopenings on the strike-off such that strike-off is adjustably mounted tothe screed using fasteners that extend through the mounting holes andthe slotted openings.
 21. The screed assembly of claim 1 wherein thescreed includes slotted openings and the strike-off includes mountingholes which are aligned with the slotted openings on the screed suchthat strike-off is adjustably mounted to the screed using fasteners thatextend through the mounting holes and the slotted openings.
 22. A screedassembly for leveling and compacting paving material within a pavingmachine, the screed assembly comprising: a strike-off for shearing upperportions of a mass of paving material that is deposited forwardly of thescreed assembly by the paving machine; and a screed coupled to thestrike-off, the screed including a front portion, a rear portion and arounded portion positioned between the front portion and the rearportion such that the front portion of the screed prevents the pavingmaterial from flowing over on top of the screed and is instead channeledby the rounded portion to flow beneath a leveling surface on the rearportion in order to level and compact the paving material.
 23. A screedassembly for use with a paving machine, the screed assembly comprising:a one-piece screed including a front portion, a rear portion and arounded portion positioned between the front portion and the rearportion, the front portion of the screed including a front surface andthe rear portion of the screed including a lower leveling surface forcompacting paving material; and a strike-off including at least oneblade such that each of the blades includes a rear surface which iscoupled to the front surface on the front portion of the screed.
 24. Thescreed assembly of claim 1 wherein the strike-off and screed eachinclude aligned mounting holes and the strike-off is connected to thescreed using fasteners that extend through the aligned mounting holes.